THE INTELLIGENCE OF MAMMALS 235 



of course have been the result of the dog's studying the 

 hinges, latch and general make-up of the gate, and conclud- 

 ing that if the latch were raised the gate would be free to 

 swing open. Such a course would be a very natural one 

 for a human being, but few would consider that a dog 

 would be likely to follow it. The dog might, however, 

 learn to open the gate by watching someone do it and then 

 imitating him. In this case the dog might be thought to 

 conclude that "since a man lifted the latch and went out, 

 therefore, I can lift the latch and go out." As a matter of 

 fact the dog learned to make his escape in neither of these 

 ways. His method of learning the trick which was watched 

 from the beginning was as follows: Being placed in the 

 yard from which he was anxious to escape Toby poked his 

 head between the bars of the fence in various places and by 

 chance placed it under the latch and raised it, when the 

 gate swung open and he scampered out on the street. The 

 method pursued was one of trial and error. The fortunate 

 movement which effected the dog's liberation was associated 

 with the perception of the latch, but the association was not 

 perfect at first. Only after ten or twelve experiences, in 

 which the number of times the dog poked his nose through 

 wrong places gradually diminished, did he learn to go 

 directly to the right place, and raise the latch. 



The experiments of Thorndike have convinced him that 

 the intelligence of animals is limited to the type that we 

 have just considered. He holds that animals do not draw 

 inferences and that, barring the apes, it is doubtful if they 

 have ideas. Thorndike's experiments were among the 

 first systematic attempts to get at the nature and limitation 

 of animal intelligence by means of experimental methods. 

 Through his pronounced spirit of iconoclasm toward anec- 

 dotal psychology and anthropomorphism Thorndike was 



